JP2638436B2 - Switching regulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching regulator, and more particularly to a switching regulator having a backup function when an input voltage is interrupted.

[0002]

2. Description of the Related Art A conventional switching regulator of this type includes a first converter 71 as shown in FIG.
And the second converter 72 are connected via a diode 73, and the input side of the second converter 72 is connected to a battery 75 via a diode 74.
Here, the output voltage of the first converter 71 is set higher than the voltage of the battery 75, and in the normal state,
To prevent energy from being released.

When the power supply to the input terminals 1 and 2 is cut off, or when the output voltage of the first converter 71 becomes lower than the voltage of the battery 75 for some reason, the battery 75 Diode 7 to 2 converter 72
4, the energy is supplied via the output terminals 11,
12, a predetermined output voltage is continuously output.

[0004]

In the above-described conventional switching regulator, two converters are connected to provide a backup function when the input voltage is cut off, and two converters are operated during a normal operation, and when the input voltage is cut off. One converter is operating. However, the efficiency at the time of normal operation is the product of the efficiencies of the converters, which is extremely lower than the efficiency at the time of input voltage interruption. Therefore, not only must heat dissipation be taken into consideration, but the elements used must also be selected with sufficient ratings.
Furthermore, the use of two converters is heavy, large and expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a switching regulator having a backup function when an input voltage is interrupted, which is more efficient, smaller, lighter, and lower in cost.

[0006]

A switching regulator according to the present invention comprises a transformer having a primary winding and a secondary winding for output, and a DC input which is turned on and off in response to a first drive pulse. A first switching element for supplying to the output, a battery having one end connected to the output secondary winding,
A second switching element connected in series with the battery and turned on / off in response to a second drive pulse to supply a current from the battery to the output secondary winding; A rectifier circuit that rectifies a voltage to generate a DC output; an input monitoring unit that detects that the DC input has dropped below a predetermined value; an output voltage detection unit that detects a voltage of the DC output; Operation switching means for supplying the second drive pulse to the second switching element to operate when the means detects a decrease in the DC input;
First pulse generating means for receiving the DC input and generating a first reference pulse having a predetermined period; and receiving the first reference pulse and controlling the output voltage in accordance with a voltage detected by the output voltage detecting means. First pulse control means for controlling the pulse width so as to output the first drive pulse, and second pulse generating means for receiving the DC output and generating a second reference pulse having a predetermined period. And a second pulse which receives the second reference pulse, controls the pulse width so that the output voltage becomes constant in accordance with the voltage detected by the output voltage detection means, and outputs the pulse as the second drive pulse Control means. In addition, the apparatus further comprises charging means for rectifying the voltage induced in the output secondary winding by a multiple voltage and charging the battery when the DC input is normal, and the input monitoring means adjusts the voltage of the charging means. It may be configured to monitor.

A switching regulator according to the present invention includes a transformer having a primary winding, an output secondary winding, and a feedback secondary winding, and a DC input that is turned on / off in response to a first drive pulse. A first switching element for supplying to the primary winding, a battery connected between one end of the output secondary winding and one end of the feedback secondary winding, and one end connected to the battery. A second switching element that is connected and turned on / off in response to a second drive pulse to supply current from the battery to the output secondary winding; and rectifies a voltage induced in the output secondary winding. A rectifier circuit for generating a DC output; input monitoring means for detecting that the DC input has dropped below a predetermined value; output voltage detecting means for detecting a voltage of the DC output; and The second An operation switching unit that supplies the second drive pulse to the switching element to operate the switching device, a first pulse generation unit that receives the DC input and generates a first reference pulse having a predetermined period, and the first reference First pulse control means for receiving a pulse and controlling the pulse width so that the output voltage becomes constant in accordance with the voltage detected by the output voltage detection means and outputting the pulse as the first drive pulse; A pulse is generated by a voltage induced in the secondary winding, and a pulse width is controlled so that the output voltage is constant according to the voltage detected by the output voltage detection means, and the pulse is output as the second drive pulse. And second pulse control means. In addition, the apparatus further comprises charging means for rectifying the voltage induced in the output secondary winding by a multiple voltage and charging the battery when the DC input is normal, and the input monitoring means adjusts the voltage of the charging means. It may be configured to monitor.

A switching regulator according to the present invention includes a transformer having a primary winding, an output secondary winding, and a charging secondary winding, and a DC input that is turned on and off in response to a first drive pulse. A first switching element that supplies the primary winding, a rectifier circuit that rectifies a voltage induced in the output secondary winding to generate a DC output, and one end connected to the output secondary winding. A second switching element connected in series with the battery and turned on / off in response to a second drive pulse to supply current from the battery to the secondary winding for output; and the secondary winding for charging. A charging means for rectifying the voltage induced in the line by multiplying the voltage and charging the battery when the DC input is normal; and monitoring the voltage of the charging means to detect that the DC input has dropped below a predetermined value. Input monitoring means for Output voltage detection means for detecting a voltage of a force, operation switching means for supplying the second drive pulse to the second switching element to operate when the input monitoring means detects a decrease in the DC input, A first step of receiving the DC input and generating a first reference pulse having a predetermined period;
Receiving the first reference pulse and controlling the pulse width so that the output voltage becomes constant in accordance with the voltage detected by the output voltage detecting means, and outputting the pulse as the first drive pulse A first pulse control unit, a second pulse generation unit that receives the DC output and generates a second reference pulse having a predetermined period, and a voltage detected by the output voltage detection unit that receives the second reference pulse. And a second pulse control means for controlling a pulse width so that the output voltage becomes constant in accordance with the second drive pulse and outputting the second drive pulse.

A switching regulator according to the present invention includes a transformer having a primary winding, an output secondary winding, a charging secondary winding, and a feedback secondary winding, and a DC input to a first drive pulse. A first switching element that is turned on / off in response to and supplies the primary winding, and a battery connected between one end of the output secondary winding and one end of the feedback secondary winding. A second switching element having one end connected to the battery and turned on / off in response to a second drive pulse to supply a current from the battery to the output secondary winding; and A rectifying circuit that rectifies the induced voltage to generate a DC output, and a charging unit that rectifies the voltage induced in the charging secondary winding by a multiple voltage and charges the battery when the DC input is normal; The voltage of the charging means is monitored to determine that the DC input has a predetermined value. Input monitoring means for detecting that the voltage has dropped below; output voltage detection means for detecting the voltage of the DC output; and when the input monitoring means has detected a decrease in the DC input, the second switching element is connected to the second switching element. Operation switching means for supplying and operating the second driving pulse, first pulse generating means for receiving the DC input and generating a first reference pulse of a predetermined period, and receiving the first reference pulse and outputting the first reference pulse. First pulse control means for controlling a pulse width so that the output voltage becomes constant in accordance with the voltage detected by the voltage detection means and outputting the pulse as the first drive pulse; A pulse is generated by a voltage, and the pulse width is controlled so that the output voltage becomes constant in accordance with the voltage detected by the output voltage detection means.
And a second pulse control means for outputting as a drive pulse of the second pulse.

A switching regulator according to the present invention includes a transformer having a primary winding and an output secondary winding, and a first switching for turning on / off a DC input in response to a first pulse and supplying the DC input to the primary winding. An element, a rectifier circuit for rectifying a voltage induced in the output secondary winding and sending a DC output to an output terminal, a battery, and multiply-voltage rectifying the voltage induced in the output secondary winding. Charging means for charging the battery, input monitoring means for monitoring the voltage of the charging means to detect that the DC input has dropped below a predetermined value, and a stabilizing circuit for stabilizing the output of the battery. A switch connected between the stabilizing circuit and the output terminal, the switch being operated when the input monitoring means detects a decrease in the DC input, and transmitting an output of the stabilizing circuit to the output terminal. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. An AC input is rectified and smoothed by a rectifier circuit (not shown), supplied to input terminals 1 and 2, and a DC output of a predetermined voltage is provided. Are output from terminals 11 and 12.

Here, the input monitoring circuit 3 has input terminals 1 and 2.
The DC input voltage supplied to the power supply 2 is monitored, and when the DC input voltage falls below a predetermined value is detected, a detection signal S1 is transmitted. The pulse generation circuit 4 generates a reference pulse P0 having a predetermined cycle. The pulse width control circuit 5 outputs a drive pulse P1 by controlling the pulse width of the pulse P0 according to the impedance change of the light receiving portion of the photocoupler 16. The switching element 6 turns on and off the current supplied to the primary winding of the transformer 7 according to the drive pulse P1. Diode 8 and capacitor 9 connected to the secondary winding side of transformer 7 rectify and smooth the voltage generated in the secondary winding and send it to output terminals 11 and 12.

The shunt regulator element 13 includes a resistor 1
The output terminal voltages divided by 4 and 15 are respectively received by reference terminals, and the photocoupler 1
By controlling the current flowing through the light emitting units 6 and 17,
The impedance of the light receiving sections of the photocouplers 16 and 17 is changed.

The pulse generator 19 on the secondary side of the transformer comprises:
Like the pulse generation circuit 4, the reference pulse P0 having a predetermined period is generated. The pulse width control circuit 20 outputs a drive pulse P2 by controlling the pulse width of the reference pulse P0 according to the impedance change of the light receiving section of the photocoupler 17. Switching element 21 starts operating in response to drive pulse P2 when switch circuit 23 is turned off, and turns on and off the current supplied from battery 22 to the secondary winding of transformer 7.

The switch circuit 23 is normally in an ON (closed) state. However, when the switch circuit 23 receives the detection signal S1 from the input monitoring circuit 3, that is, the DC voltage supplied to the input terminals 1 and 2 becomes lower than a predetermined value. When the voltage drops, the driving pulse P2 is applied to the switching element 21 in an off (open) state.
Here, the pulse generating circuit 4 on the input terminal side is set so as to stop operating when the input DC voltage falls below a predetermined value, and the switching element 6 starts operating at the same time as the switching element 6 starts operating. Stop operation. Therefore, when a normal DC voltage is supplied to the input terminals 1 and 2, the switching element 6 operates and the switching element 21 stops operating.

Next, the operation will be described.

When a normal DC voltage is supplied to the input terminals 1 and 2, the primary winding of the transformer 7 is supplied with a current that is turned on and off by the switching element 6. The electric energy is stored in the transformer 7 as magnetic energy during the ON period of the switching element 6, and is output to the secondary winding side as electric energy during the OFF period. The output of the secondary winding is rectified and smoothed by a diode 8 and a capacitor 9 and supplied to output terminals 11 and 12 as a DC output.

When the DC voltage supplied to the input terminals 1 and 2 drops below a predetermined value, the switch circuit 23 receives the detection signal S1 from the input monitoring circuit 3 and turns off as shown in FIG. The switching element 21 has a drive pulse P
The operation is started according to 2. When the switching element 21 is on, a current flows from the battery 22 through the secondary winding of the transformer 7, and when the switching element 21 is turned off, a back electromotive force occurs in the secondary winding of the transformer 7. Electric power is generated. The diode 8 and the capacitor 9 rectify and smooth the back electromotive force and output it to the output terminals 11 and 12 as a DC output.

By the way, the pulse width control circuits 5 and 20
The pulse width is controlled in accordance with the impedance change of the light receiving sections of the photocouplers 16 and 17, respectively. In this case, the DC voltage at the output terminals 11 and 12 increases and the photocouplers 16 and 1
As the current flowing through 7 increases, the pulse width is controlled to be narrowed and the duty cycle is reduced, and the output voltage at output terminals 11 and 12 is controlled to be constant.

As described above, by using a single transformer having primary and secondary windings to constitute a switching regulator with a backup function, there is no need to connect two stages of converters as in the conventional example, and the efficiency is reduced. It is possible to reduce the size, weight, and cost. Further, since the switching circuit and the battery including the second switching element can be arranged on the secondary side which is insulated from the primary side of the transformer and has a low voltage, the mounting design in consideration of safety becomes easy and the size can be reduced. Instead, safety during maintenance can be ensured.

FIG. 2 is a block diagram showing a second embodiment of the present invention. The same components as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals.

Here, the difference from the first embodiment is the first embodiment.
The switching element 21 of the embodiment is the pulse generation circuit 10
Is separately excited based on the reference pulse P0 of the
This embodiment is characterized in that the switching element 21 performs a self-excited oscillation operation. Therefore, the transformer 26 having the feedback winding
And a pulse width control circuit 25 that generates a pulse in accordance with a voltage induced in the feedback winding and controls a pulse width in accordance with a change in impedance of the light receiving portion of the photocoupler 17 to output a drive pulse P3. Have.

When a normal DC voltage is supplied to the input terminal, the switching element 6 turns on and off the supply current of the primary winding of the transformer 26 in response to the drive pulse P1, and supplies a constant voltage to the output terminals 11 and 12. Output DC.

When the input DC voltage falls below a predetermined value, the switch circuit 23 receives the detection signal S1 from the input monitoring circuit 3 and turns off as shown in FIG.
A minute current flows from the battery 22 via the resistor 24 to the control terminal of the switching element 21. As a result, a current flows through the switching element 21 and a voltage is induced in the feedback winding of the transformer 26. The pulse width control circuit 25 generates a pulse according to the voltage induced in the feedback winding, controls the pulse width so as to keep the output voltage constant, and outputs the pulse as the drive pulse P3.

By causing the switching element 21 to perform the self-excited oscillation operation, the pulse generating circuit 19 used in the first embodiment can be omitted.

FIG. 3 is a block diagram showing a third embodiment of the present invention. The same components as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals.

Here, the difference from the first embodiment is that when a normal DC voltage is supplied to the input terminal, the battery 22
Is added, and an input monitoring circuit is provided on the secondary side of the transformer. Therefore, a transformer 34 having an output secondary winding L2a and a charging secondary winding L2b, a rectifying circuit 31 for rectifying the output of the charging secondary winding L2b, and a charging current supplied to the battery 22 are provided. A charge control circuit 32 for controlling the rectifier circuit 31 and an input monitor circuit 33 for monitoring the voltage of a part of the rectifier circuit 31 to detect when the input DC voltage has dropped below a predetermined value and transmitting a detection signal S2.
Are provided.

Next, differences from the first embodiment will be mainly described.

When a normal DC voltage is supplied to the input terminal, predetermined voltages are generated in the output secondary winding L2a and the charging secondary winding L2b of the transformer 34, respectively. The output of the output secondary winding L2a is rectified and smoothed by the diode 8 and the capacitor 9, and the output terminal 11,
12 is supplied as a DC output. The output of the charging secondary winding L2b is rectified and smoothed by the rectifier circuit 31.

Here, the rectifier circuit 31 uses a voltage doubler rectifier circuit composed of a rectifier element and a capacitor. By using a multiple voltage rectifier circuit such as a triple voltage rectifier circuit or a quadruple voltage rectifier circuit, various charging voltages can be handled. The charge control circuit 32 includes the rectifier circuit 3
1 to supply a charging current to the battery 22 by controlling the rectified output. When the input DC voltage falls below a predetermined value, the battery 2
When the discharge is started from 2, charging is stopped. The input monitoring circuit 33 monitors the voltage across the capacitor C1 constituting the rectifier circuit 31 and detects when the input DC voltage has dropped below a predetermined value.

By doing so, the switching circuit including the second switching element and the battery are arranged on the secondary side which is insulated from the primary side of the transformer and has a low voltage. Not only can the mounting design be simplified and the size can be reduced, but also safety during maintenance can be ensured. Also, an input monitoring circuit can be arranged on the secondary side of the transformer, and charging and input monitoring can be performed by the output of the secondary winding for charging, so that the circuit can be miniaturized. By using, various charging voltages can be handled.

FIG. 4 is a block diagram showing a fourth embodiment of the present invention. The same components as those in the second embodiment shown in FIG. 2 are denoted by the same reference numerals, and differences from the second embodiment are mainly shown.

Here, the difference from the second embodiment is that when a normal DC voltage is supplied to the input terminal, the battery 22
Is added, and an input monitoring circuit 33 is provided on the secondary side of the transformer. Therefore, the transformer 35 having the output secondary winding L2a, the charging secondary winding L2b, and the feedback secondary winding L2f, respectively, and the rectifier circuit 31 for rectifying the output of the charging secondary winding L2b. , Battery 2
A charge control circuit 32 for controlling a charge current supplied to the power supply 2;
An input monitoring circuit 33 for monitoring the voltage from the rectifier circuit 31 to detect when the input DC voltage has dropped below a predetermined value and transmitting a detection signal S2 is provided.

The rectifier circuit 31, the charge control circuit 32,
The configuration and connection of the input monitoring circuit 33 are the same as those of the third embodiment shown in FIG. 3, and the fourth embodiment has the effects of the second and third embodiments.

FIG. 5 is a block diagram showing a fifth embodiment of the present invention. The same components as those of the third embodiment shown in FIG. 3 are denoted by the same reference numerals.

Here, the difference from the third embodiment is that the output of the secondary winding for output of the transformer 41 is rectified and the battery is charged, so that the transformer 34 of the third embodiment is changed. The point is that the secondary winding for charging that it had was unnecessary. For this reason,
A transformer 41 whose secondary winding is designed with a capacity having a margin for charging; a rectifier circuit 31 connected to the secondary winding;
A charge control circuit 36 connected in series to the negative output of the rectifier circuit 31 is provided.

Since the positive output of the rectifier circuit 31 needs to be directly connected to the secondary winding, the charge control circuit 36 is set to the positive electrode ground control. Further, the input monitoring circuit 33 receives the rectified output of the rectifier circuit 31 connected to the secondary winding and detects a drop in the input DC voltage. Since the output fluctuation of the rectifier circuit 31 is small with respect to the fluctuation of the input DC voltage, the detection sensitivity is slightly inferior, but there is no practical problem.

This eliminates the need for a secondary winding for charging, so that in the case of a transformer having a large number of outputs, an unnecessary increase in the size of the pin terminal can be prevented.

FIG. 6 is a block diagram showing a sixth embodiment of the present invention. The same components as those of the fifth embodiment shown in FIG.

Here, the difference from the fifth embodiment is that when the input DC voltage falls below a predetermined value, the output of the battery is controlled to a predetermined voltage and sent out, so that the secondary side switching is performed. That is, no element is required. For this purpose, a voltage stabilizing circuit 43 for converting the output voltage of the battery 42 into a predetermined voltage and a power supply switch 44 which operates upon receiving the detection signal S2 from the input monitoring circuit 33 are provided. The rectifier circuit 31, the charge control circuit 32, the input monitoring circuit 3,
The configuration and connection of the third embodiment are the same as those of the third embodiment shown in FIG.

The power supply switch 44 is connected to the input monitoring circuit 3
3 is turned on (closed) in response to the detection signal S2 from
The DC output converted to a predetermined voltage by the voltage stabilizing circuit 43 is sent to the output terminals 11 and 12. Here, the voltage of the battery 42 is set higher, and a multiple voltage rectifier circuit is used for the rectifier circuit 31. With this configuration,
No secondary side switching element is required, reducing size and weight,
The price can be reduced.

[0043]

As described above, according to the present invention, when the input is disconnected or the voltage drops below a predetermined value, this is detected and the second switching element is operated, so that the secondary winding of the transformer is converted from the battery. A single transformer having primary and secondary windings is used by turning on and off the current supplied to the secondary winding to generate a counter electromotive force in the secondary winding and rectifying this to obtain a DC output. As a result, a switching regulator with a backup function can be configured, so that there is no need to connect two stages of converters as in the conventional example, and efficiency, size, weight, and cost can be reduced. Further, since the switching circuit and the battery including the second switching element can be arranged on the secondary side which is insulated from the primary side of the transformer and has a low voltage, the mounting design in consideration of safety becomes easy and the size can be reduced. Instead, safety during maintenance can be ensured.

Further, by providing a secondary winding for feedback in the transformer and causing the second switching element to perform a self-excited oscillation operation, a pulse generation circuit for driving the second switching element can be eliminated, thereby simplifying the operation. it can.

Further, even if a secondary winding for charging is provided in the transformer to charge and monitor the input of the battery, the circuit can be downsized, and a multiple voltage rectifying circuit can be used as a rectifying circuit for charging. By using, various charging voltages can be handled.

Further, a transformer having an output secondary winding designed with a capacity having a margin for charging is used, and the output of the output secondary winding is rectified to charge the battery. This eliminates the need for a secondary winding for charging, so that in the case of a transformer having a large number of outputs, it is possible to prevent an unnecessary increase in size for a pin terminal.

Further, when the input is cut off or the voltage drops below a predetermined value, the output of the battery is controlled to a predetermined voltage and sent out, so that the secondary-side switching element becomes unnecessary, so that the size and weight can be reduced and the cost can be reduced. Can be measured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

FIG. 4 is a block diagram showing a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a fifth embodiment of the present invention.

FIG. 6 is a block diagram showing a sixth embodiment of the present invention.

FIG. 7 is a block diagram illustrating an example of a conventional switching regulator.

[Explanation of symbols]

 1, 2 input terminal 3, 33 input monitoring circuit 31 rectifier circuit 4, 19 pulse generation circuit 5, 20 pulse width control circuit 6, 21 switching element 7, 26, 34, 35 transformer 11, 12 output terminal 23, 46 switch Circuit 22, 42 Battery S1, S2 Detection signal P0 Reference pulse P1, P2, P3 Drive pulse

Claims (6)

(57) [Claims] A transformer having a primary winding and a secondary winding for output; a first switching element for turning on and off a DC input in response to a first drive pulse and supplying the DC input to the primary winding; A battery having one end connected to the output secondary winding;
A second switching element connected in series with the battery and turned on / off in response to a second drive pulse to supply a current from the battery to the output secondary winding; A rectifier circuit that rectifies a voltage to generate a DC output; an input monitoring unit that detects that the DC input has dropped below a predetermined value; an output voltage detection unit that detects a voltage of the DC output; Operation switching means for supplying the second drive pulse to the second switching element to operate when the means detects a decrease in the DC input;
First pulse generating means for receiving the DC input and generating a first reference pulse having a predetermined period; and receiving the first reference pulse and controlling the output voltage in accordance with a voltage detected by the output voltage detecting means. First pulse control means for controlling the pulse width so as to output the first drive pulse, and second pulse generating means for receiving the DC output and generating a second reference pulse having a predetermined period. And a second pulse which receives the second reference pulse, controls the pulse width so that the output voltage becomes constant in accordance with the voltage detected by the output voltage detection means, and outputs the pulse as the second drive pulse A switching regulator comprising control means. 2. A transformer having a primary winding, an output secondary winding, and a feedback secondary winding, and a DC input is turned on / off in response to a first drive pulse and supplied to the primary winding. A first switching element, a battery connected between one end of the output secondary winding and one end of the feedback secondary winding, and a second end connected to the battery. A second switching element that is turned on / off in response to a drive pulse to supply current from the battery to the output secondary winding, and rectifies a voltage induced in the output secondary winding to generate a DC output Rectifier circuit, input monitoring means for detecting that the DC input has dropped below a predetermined value, output voltage detecting means for detecting the voltage of the DC output, and the input monitoring means has detected a drop in the DC input. When the second drive element is connected to the second switching element. Operation switching means for supplying and operating the pulse, first pulse generating means for receiving the DC input and generating a first reference pulse of a predetermined period, and output voltage detecting means for receiving the first reference pulse A first pulse control means for controlling a pulse width so that the output voltage becomes constant in accordance with the voltage detected by the control means and outputting the pulse as the first drive pulse; and a voltage induced in the feedback secondary winding. And generating a pulse as the second drive pulse by controlling the pulse width so that the output voltage is constant according to the voltage detected by the output voltage detection means.
And a pulse control means. And a charging means for rectifying the voltage induced in the secondary winding for output by multiplying the voltage and charging the battery when the DC input is normal. The switching regulator according to claim 1, wherein the voltage of the switching regulator is monitored. 4. A transformer having a primary winding, an output secondary winding, and a charging secondary winding, and a DC input is turned on / off in response to a first drive pulse and supplied to the primary winding. A first switching element, a rectifier circuit for rectifying a voltage induced in the output secondary winding to generate a DC output, a battery having one end connected to the output secondary winding, A second switching element connected in series with the battery and turned on / off in response to a second drive pulse to supply a current from the battery to the output secondary winding; and a voltage induced in the charging secondary winding. Charging means for multiplying voltage and rectifying the battery when the DC input is normal, and input monitoring means for monitoring the voltage of the charging means and detecting that the DC input has dropped below a predetermined value. Output voltage detecting means for detecting the voltage of the DC output An operation switching unit that supplies the second drive pulse to the second switching element to operate when the input monitoring unit detects a decrease in the DC input; A first pulse generation means for generating one reference pulse, and a pulse width controlled so as to receive the first reference pulse and to make the output voltage constant in accordance with a voltage detected by the output voltage detection means. First pulse control means for outputting the first drive pulse, second pulse generation means for receiving the DC output to generate a second reference pulse having a predetermined period, and receiving the second reference pulse. A second pulse control unit that controls a pulse width so that the output voltage is constant according to the voltage detected by the output voltage detection unit and outputs the pulse width as the second drive pulse. Switching regulator. 5. A transformer having a primary winding, a secondary winding for output, a secondary winding for charging, and a secondary winding for feedback, and turning on / off a DC input in response to a first drive pulse. A first switching element for supplying to the primary winding, a battery connected between one end of the output secondary winding and one end of the feedback secondary winding, A second switching element connected to a battery and supplying current to the output secondary winding from the battery by turning on and off in response to a second drive pulse; and rectifying a voltage induced in the output secondary winding. A rectifier circuit for generating a DC output, a charging means for rectifying the voltage induced in the charging secondary winding by a multiple voltage and charging the battery when the DC input is normal, and a voltage of the charging means. Monitoring that detects that the DC input has dropped below a predetermined value. Means, an output voltage detecting means for detecting a voltage of the DC output, and supplying the second drive pulse to the second switching element when the input monitoring means detects a decrease in the DC input to operate the input switching means. An operation switching unit, a first pulse generation unit that receives the DC input and generates a first reference pulse having a predetermined period, and receives the first reference pulse and responds to a voltage detected by the output voltage detection unit. First pulse control means for controlling the pulse width so that the output voltage is constant and outputting the first drive pulse as the first drive pulse; and generating a pulse by a voltage induced in the feedback winding and generating the output voltage. A second pulse control unit that controls a pulse width so that the output voltage is constant according to the voltage detected by the detection unit and outputs the pulse width as the second drive pulse. Switching regulator that. 6. A transformer having a primary winding and a secondary winding for output, a first switching element for turning on and off a DC input in response to a first pulse and supplying the DC input to the primary winding;
A rectifier circuit for rectifying a voltage induced in the secondary winding for output and sending a DC output to an output terminal; a battery; Charging means for charging the battery, input monitoring means for monitoring the voltage of the charging means to detect that the DC input has dropped below a predetermined value, and a stabilizing circuit for stabilizing the output of the battery,
A switch that is connected between the stabilizing circuit and the output terminal and that operates when the input monitoring unit detects a decrease in the DC input and sends out the output of the stabilizing circuit to the output terminal. A switching regulator characterized by the following.